Originally Posted by dotKaZE
I must disagree with you about Backstep and Quick Rebound, and here is why.
Putting aside reduced SP cost/Backstep + Cancel from the start patch in DnF, Backstep and Cancel costs 100 SP. This is vital SP that could be used in other skills, perhaps five levels into an active for the Cancel with extra SP, maybe last three levels to late-level skills. Not every class needs it.
Fighters, it is debatable. Personally, I don't think we need it. Our mobility is high already, it's neither used for combos, which is what we should focus on, nor is it really used to avoid attacks at all.
Mages, it would depend. Summoners and Elementalists don't need it, they shouldn't exactly be in close-range combat. Battlemages and Witches could find uses it in, but Witches tend to dash into air combos automatically, while Battlemages usually run and slam enemies with their long forward range.
Gunners probably have the best use for this. They spam shots and cancel to continue quickly.
Priests have some uses since their attacks are usually slow to cancel, but physical Exorcists spam super armor, magical Exorcists are asses with their circle crap, Monks have Sway like you said, and Crusaders... ANYWAYS.
Slayers primarily only use it for Backstep Cutter. Cancel - Triple Slash would serve better with more adjustable SP usage and multi-purposed anyways.
As for Quick Rebound, I honestly don't know why you would waste a nice 10 SP on it. Not only are you restricted from doing ANYTHING in the time of your invincibility, enemies can do a prolong frame attack that will hit you as soon as Quick Rebound goes away. SURE, it MAY be useful to avoid OTG strings or relaunches, but the use of it is still limited, as you'll probably eat more damage after they re-combo you out of Quick Rebound than if you took OTG/relaunch.
Going by prerequisites is just... ehhhhhhhhhhh.
It's better to go based on a combo you'd attempt to try, because more than likely, you'll be getting skills that have a Cancel (other than maybe non-Ranger-like Gunners) that strings together.
No skills give invincibility frame on activation. The only skills giving invincibility frames are those that give grab decision and ACTUALLY LAND, thus Grapplers have too much of that. Brawler Explosive Hook gives invincibility frame on explosion. Nen Master's Nen Guard is TECHNICALLY invincible, even if you can destroy the dome. Priest grab thing that slams you into an invisible wall. Slayer Neutral Wave Wheel and Bloodlust. Gunner Punisher on hit. Witches with ICE CAR I think.
Waste 10 SP on it? It's only 10 SP for a skill that allows you to stand up faster and avoid horrible death. Yeah, it can get you into trouble sometimes but I rarely find the instance where using quick rebound is less safe than sitting on the ground. (Unless the enemy is far away and then it doesn't really matter!) If it says anything, a brawler would eat you alive if you didn't have quick rebound unless you like getting mounted.
Far as backstep is concerned, I've yet to find anyone who has gotten it and regretted getting it. It's just useful, overly pricey sure but unparalleled in it's usefulness.